Clarity, legibility and safetyusing universally understood symbols

and units of measurement

A major upgradefor Britain’s road signs

2.0SignsTraffic

The 1968 Vienna Convention on Road Signs and Signalsstipulates metric-only for restriction signs.

Airports, garage forecourts, warehouses, and many carparksuse metric-only restriction signs.

Vehicle owner's manuals give vehicle dimensions in metric.

The continued use of imperial restriction signs is a serioussafety issue in bridge strikes involving foreign lorries.safety issue in bridge strikes involving foreign lorries.UK drivers are generally familiar with imperial and metricunits, but foreign drivers have no understanding of imperial.

Supplementary metric signs have been used since 1981.The full switchover to metric-only is overdue.

Hundreds of foreign lorries pass this 6'-6" width restriction sign every day

Maximum magneticflux density 7.5 teslas ?

'T' is the symbol for tesla (the SI unit ofmagnetic flux density).

The correct symbol for tonne is 't'.

The symbols used on road signs forfeet and inches are also incorrect.The symbols, as listed in the Units ofMeasurement Regulations 1986, areMeasurement Regulations 1986, are'ft' and 'in'.

The abbreviation 'm g w' addsunnecessary clutter to the sign, andrelies on the driver knowing that it isan English abbreviation for 'maximumgross weight'.

The standard symbol for metre is 'm'.To also use 'm' as an abbreviation for mile causes confusion.Most directional signs use the word 'miles' or no abbreviation.

Services 20 metres ahead ?

3. Width, height & length in metres only

2. Use t for tonne, not T

1. Use m for metres, not for miles

For a given text height, the numericcharacters used to express fractions ofa mile are smaller than the charactersused for whole numbers, and aretherefore less readable at a givendistance.

e.g. e.g. '¼ m' is not as legible as '400 m'.

In a tunnel fire, confusion can cost lives.Distances to exits should be shown inuniversally understood metres, as perthe diagrams in the Vienna Convention.

Traffic Signs Manual - Chapter 8 Part 1

Always use the standardsymbol 'm'. This shouldalways be lower case.

Avoid language specificwords such as'metres' and 'metr',and other improvisedand other improvisedabbreviations.

All road design and construction is carried out using metres.e.g. Sign positions at roadworks are specified in multiples of100 m, yet these distances are labelled as yards on the signs.

Highway Code stopping distances are in metres, not yards.

The metre is the standard unit of distance on road signsin all other countries, except the USA where feet are used.

Britain is the only country in the worldstill using yards on road signs.

The size and cost of bilingual roadsigns can be reduced by using thesymbol 'm', instead of 'yards' and 'llath'.

In Wales, distances cannot be shownin 'yards', unless they are also shownin 'llath'. Unlike imperial units, metricsymbols do not require translation.

5. Do not use fractions

4. Short distances in metres only

2

Metric odometers willbe able to be usedmeaningfully both athome and whendriving outside the UK.

In Wales, the word'miles' can only be'miles' can only beused with 'milltir'.

Measuring fuelconsumption instandard L/100 kmwill become possible.(mpg has beenimpractical sinceimpractical sincegallons were phasedout in the 1980s).

CO emissions aremeasured in g/km.

UK vehicle odometers count in units of 0.1 miles (528 feet).This unit does not relate readily to the yards, or fractions ofmiles, used on road signs. Switching to kilometres will meanthat new odometers will count in practical 100 m units.

All road design and construction iscarried out using metric units.

The UK's official map system usesa kilometre grid.

Most existing signs caneasily be converted tokilometres.

A driver location sign on theA38 at kilometre 420.5

Digital tachographs record km and km/h only

Always use the standardsymbol 'km'. This shouldalways be lower case.

Avoid language specificwords such as'kilometres' and 'cilometr',and other improvisedand other improvisedabbreviations.

To reduce clutter, replace the words,'For' and 'Am' on signs such as,'For 550 yards', with 'up arrows',as per the 1968 Vienna Convention.

'Up arrows' are language-independent.

Language-independentway to say'For 550 yards'

Language-dependentways to say '↑ 500 m ↑'

7. Replace miles with kilometres

6. Use 'up arrows' for hazard extent

Drivers will benefit from not having to adjust to differentsystems every time they drive outside the UK.

The UK has a land border with acountry with speed limits in km/h

Speed limits in km/h will meanthat practically every vehicleon Britain's roads will be ableto display the relevant unit.

More than 3 million foreign-registered vehicles enter theUK each year. Most of thesevehicles' speedometerscannot show speeds in mph.

Speed limits in km/h would provide Traffic Authorities with amore versatile range of speed restrictions, enabling speedlimits to be more finely tuned to individual roads.

Commercial vehicle operatorsdo not use a common systemto advertise their vehicles'metric speed limiter settingsThis lorry has a 90 km/h speed limiter

The de facto motorway speed limits for lorries and coachesare defined by speed limiter regulations which are in km/h.e.g. 90 km/h for lorries and 100 km/h for coaches.These regulations are incompatible with official motorwayand dual carriageway speed limits set in mph.

Switching to km/h will allow newvehicles to have easy-to-read singleunit speedometer displays.

Since 1977, in readiness for metricspeed limits, all new vehicles havebeen required to be fitted withspeedometers capable of showingspeeds in km/h and mph.

An easy-to-read singleunit speedometer

A cluttered dual unitspeedometer

The unrestricted black arrowsmean 'Any vehicle'

What does this sign mean tonon-English or Welsh speakers?

The information in many text onlysigns can be better conveyedusing pictograms and symbols.e.g. 'Unsuitable for heavy goodsvehicles' signs can be replacedwith standard weight or widthrestrictions, or other pictograms.restrictions, or other pictograms.

Superfluous text, e.g. 'ANY VEH',can confuse foreign drivers.

Pictograms and symbols arelanguage independent, and can beread more quickly than text.

Metric units have universallyunderstood standard symbols.understood standard symbols.

9. Redefine all speed limits in km/h

8. Use pictograms instead of text

Revision 1.0

© UK Metric Association 2009

: www.ukma.org.uk: secretary@metric.org.uk

websitee-mail

For a full report on the case for convertingroad signs to metric units read“Metric Signs Ahead”by the UK Metric Association.

ISBN 978-0-9552351-0-8

Britain has one of the best designed and consistentsystems of road signs in the world. However, twofundamental issues need to be addressed if theunderstanding of road signs is to be improved in the 21stcentury: Many current signs can only be understood bydrivers who can read English; and many can only beunderstood by those familiar with old imperial units.understood by those familiar with old imperial units.

Both of these problems can be tackled by following theprinciples of the 1968 Vienna Convention on Road Signsand Signals: Universally understood symbols andpictograms should be used wherever possible, on theassumption that not all road users will understand the locallanguage. Indeed, better use of pictograms and symbolswould reduce costs and signage clutter in would reduce costs and signage clutter in Wales, wheresigns are required to be bilingual. Unlike imperial units,standard metric symbols do not require translation.

Failure to understand road signs can be dangerous,so addressing these issues is vital if accidents are to bereduced. The number of reported bridge strikes hasdoubled to over 2,000 a year in the past decade, costingthe country millions of pounds.the country millions of pounds. Although low bridges aresign-posted, the signs are often only in feet and incheswhich are meaningless to foreign drivers.

With an increase in international traffic, the continued useof old imperial units is no longer viable; and with themajority of UK drivers educated in the metric system,and not even being taught how many yards there are ina mile, there is now every reason to drop imperial.a mile, there is now every reason to drop imperial.

The recommendations outlined in this leaflet by theUK Metric Association will provide a quantum shift in theclarity and understanding of road signs in general, and willhave other benefits, that are no less important; such asletting our children see the units, that they learn about atschool, in use in the environment around them.

What’s wrong with Britain’s road signs ?